I have 1999 TL with 181000 miles. The car starting having a hesitation problem when driving which over a few days car was barely driveable. It started and idled okay, but when taking off it had a severe hesitation. Car would begin to roll, then RPM's would drop then surge severely and barely shift thru gears. There were no codes. I feared the transmission was going bad.

A back history, at 166,000 miles my son began driving the car, Up to that I point I was using Chevron premium gas. My son starting using grocery store regular gas. At 170,000 miles a P0131 code occurred. I replaced the upstream oxygen sensor with an Autozone sensor. Problem fixed. At 1807000 miles car starting having slight hesitation problems along with another P0131 code. So I replaced the upstream oxygen sensor again with one from Autozone again. Problem fixed.

Now at 181000, since there were no codes I did not suspect the oxygen sensor at first. I added Lucas fuel treatment to gas with no changes. So I checked fuel pressure, air filter, and egr ports and everything checked okay. So I thought maybe the oxygen sensor failed again, so I replaced it with another one from Autozone. Problem fixed. For now on my son will start using Chevron premium gas again.

So is the cheaper gas killing the oxygen sensor or is the Autozone oxygen sensor not up to par?

 

perhaps both.
I always believe in OEM electronics...NGK and Denso products.

 

Pretty sure its the cheap low-tier gas burning through your cheap sensors. You're lucky it has't developed a knock from fuel detonation. If your son drives with heavy foot, this will accelerate problems caused by crappy fuel (see what I did there? LOL). Justnspace has a good point about OEM.
Put Denso sensor in, school the kid on which gas to buy and call us in the morning. Good Luck!